The Chemical Hydrolysis Study Of A Few 4-substitude Sulfonylurea Hebicides

Sulfonylurea herbicides are the most widely used AHAS inhibitors. Because of their feature of high activity, broad ranges of weed control, good selectivity, low toxicity and safety, they are widely used in agricultural production. However in recent years, it has drawn more and more people’s attention due to the environmental pollution and the subsequently planted crops injury caused by the long residue. Therefore, it is of great significance to accurately detect the hydrolysis rate, study the hydrolysis mechanism, and develop novel environmentally benign and easy-degradable sulfonylurea herbicides.The high performance liquid chromatography(HPLC) method was used to study the hydrolysis of following sulfonylurea herbicides, the commonly used herbicide in market chlorimuron-ethyl analog A and several novel 4-substituted benzene ring synthesized sulfonylurea herbicides, 3-(4,6-dimethoxy-2-pyrimidinyl)-1-(2-methoxycarbonyl-4-aminophenyl) sulfonylurea B, 3-(4,6-dimethoxy-2-pyrimidinyl)-1-(2-methoxycarbonyl-4-nitrophenyl) sulfonylurea C, 3-(4-chloro-6-methoxy-2-pyrimidinyl)-1-(2-methoxycarbonyl-4-nitrophenyl) sulfonylurea D and 3-(4- chloro-6-methoxy-2-pyrimidinyl)-1-(2-methoxycarbonyl-4-aminophenyl)sulfonylurea E. The high performance liquid chromatography was applied to study the hydrolysis of above herbicides in the absence of light conditions at 25°C.Firstly, the hydrolysis half-lives of chlorimuron-ethyl analog A and the novel herbicide 3-(4,6-dimethoxy-2-yl)-1-(2-methoxycarbonyl-4-aminophenyl) sulfonylurea B were measured at 25°C without light conditions in water p H = 5. The hydrolysis half-lives of chlorimuron-ethyl analog A and sulfonylurea B are 15.57 and 8.45 days respectively. The sulfonylurea inhibitor B shows faster hydrolysis rate than that of chlorimuron-ethyl analog A.Secondly, the optimal detection wavelength, mobile phase, flow rate, and fixed phase of HPLC parameters were determined for chlorimuron-ethyl analog A and several novel herbicides. The hydrolysis half-lives of the widely used compound chlorimuron-ethyl analog A and several novel sulfonylurea herbicides were performed by HPLC tool without light at 25°C in p H = 5 buffer solution to get their hydrolysis half-life analysis. The results indicated that the sulfonylurea herbicides with amine group at 4-position on benzene ring shows faster hydrolysis rate than those of with nitro group at 4-position on benzene ring and chlorimuronethyl analog A in p H = 5 buffer solution. The hydrolysis rate is independent of the concentration of samples. However, the hydrolysis have-lives are very sensitive the p H value of solution.